Poly(oxyalkylene) polymeric colorants have been utilized to permanently color myriad substrates, including thermoplastic resins, such as disclosed in U.S. Pat. Nos. 4,284,729, 4,507,407, and 4,751,254; polyurethane foams, such as disclosed in U.S. Pat. No. 4,846,846; aqueous and non-aqueous liquids, such as disclosed in U.S. Pat. No. 4,871,371; and have been used as fugitive tints for textiles and threads, such as disclosed in U.S. Pat. No. 4,167,510. Such colorants provide effective and stable colorations to such materials, are easily handled, and exhibit desirable migratory properties within certain substrates.
3,4,9,10-Perylene tetracarboxylic acid bisimide based colorants are well known in industry and academia due to their favorable combination of light fastness, weather and thermal stability, as well as migration resistance in a number of applications such as coatings and plastics and inks. For this reason, they have been used extensively in the especially demanding applications of the automotive industry. These materials are insoluble pigments.
Patents DE 1130099 and GB 967178 first disclosed the potential for using perylenes as fluorescent dyes with high fluorescence quantum yield and photostability. However, these materials were only slightly soluble in organic solvents. An improvement in solubility was demonstrated by Langhals, et al, in Heterocycles, 1995, 40, 477 and references cited therein. Langhals reported that certain solubilizing substituents attached at the imide nitrogen such as long chain secondary alkyl groups (swallow-tail substituents) and 2,5-di tert-butylbenzene can enhance the solubility of perylene bisimdes in common organic solvents. These perylene bisimide dyes exhibit intense yellow fluorescence in solution with a quantum yield near unity. Even with the above-enhanced solubilizing groups, however, the materials are only soluble in common organic solvents at low concentrations. More recent applications for perylene bisimide dyes include dye laser applications, n-type semiconductors, and electrophotography.
Poly(oxyalkylene) substituents attached to organic chromophors have been used to make various colorants with enhanced dispersability and/or solubility, as disclosed in U.S. Pat. No. 4,141,684, U.S. Pat. No. 5,149,800, U.S. Pat. No. 5,177,200, U.S. Pat. No. 5,240,464, U.S. Pat. No. 5,270,363, U.S. Pat. No. 5,591,833, U.S. Pat. No. 5,766,268, U.S. Pat. No. 5,935,272, U.S. Pat. No. 5,973,064, U.S. Pat. No. 5,998,621 and the references cited therein. Applications reported thus far do not include the use of poly(oxyalkylene)ated chromophoric materials, especially perylene based materials, as fluorescent security taggants.